In order to meet the demand for higher integration of semiconductor devices, use of a three-dimensional integration technique to stack semiconductor devices in three dimensions has been proposed. Systems adopting this three-dimensional integration technique utilize a bonding system for bonding substrates such as, e.g., semiconductor wafers (hereinafter referred to as “wafers”) or the like.
Such a bonding system includes a surface modifying apparatus for modifying the surfaces of first and second substrates to be bonded, a hydrophilizing apparatus for hydrophilizing the modified first and second substrates, and a bonding apparatus for bonding the hydrophilized first and second substrates by a van der Waals force and hydrogen bonding (an intermolecular force). The bonding system further includes a substrate transfer device for transferring the first and second substrates between the respective apparatuses.
However, in the aforementioned bonding system, the modifying process of the surface modifying apparatus is performed in a depressurized atmosphere. On the other hand, the transfer of the substrates by the substrate transfer device is performed in a normal pressure atmosphere. Therefore, in the aforementioned surface modifying apparatus, the switching of a chamber pressure is performed such that the atmosphere in a chamber is set to a normal pressure atmosphere when delivering the substrates to and from the transfer device and is set to a depressurized atmosphere when performing the modifying process.
In the surface modifying apparatus, it takes time to switch the chamber pressure because the volume of the chamber is relatively large. Therefore, in the aforementioned bonding system, there is room for further improvement in terms of shortening the processing time of the substrates.